Vitamin D could keep people healthier

Studies show impact on cancer, flu

Studies show impact on cancer, flu

April 03, 2007|By John Fauber, Milwaukee Journal Sentinel

MILWAUKEE - It seems too simple to be true: Expose most of your body to about 15 minutes of sunlight a day during the summer and take large doses of inexpensive vitamin D pills during the winter and maybe, just maybe, you will substantially reduce the risk of getting various cancers, the flu, diabetes, heart disease, autoimmune diseases and neurological disorders. A flurry of research in the last few years suggests that low levels of vitamin D, a fairly common occurrence in those who live in northern locales much of the year, may be partly to blame for much of the ill health of many Americans. "Vitamin D is not just for bones anymore," said Hector Deluca, a pioneering vitamin D researcher at the University of Wisconsin-Madison. Deluca noted that the vitamin plays a role in shutting down or activating at least 100 genes, many of which are involved in preventing diseases. Consider these recent developments:

A small observational study by University of Wisconsin researchers published online last month showed a significant association between low levels of vitamin D in the blood of Alzheimer's patients and poor performance on a cognitive test. The study was prompted after family members of the Alzheimer's patients reported how well they were performing and acting within weeks of being put on large doses of prescription vitamin D, said lead author Robert Przybelski, an associate professor of geriatric medicine at the University of Wisconsin. The study noted that neurons, like many other cells, have vitamin D receptors. It said vitamin D might enhance levels of important brain chemicals and that it also might help protect brain cells.

Earlier this month, an analysis in the American Journal of Preventive Medicine looked at vitamin D levels in the blood and concluded that daily intake of 1,000 to 2,000 international units of the supplement could reduce the incidence of colorectal cancer by about 50 percent with little risk. The current recommended intake ranges from about 200 IU in children to 600 IU in the elderly.

Also this month, many of the same researchers concluded in a separate analysis that intake of 2,000 IU of vitamin D and, when possible, about 12 minutes a day of sun exposure could reduce the incidence of breast cancer by about 50 percent. Vitamin D has the potential to reduce at least half of serious invasive cancers and make the remaining ones milder and far more treatable, said Cedric Garland, a co-author on both papers and professor of family and preventive medicine at the University of California-San Diego and the Moores Cancer Center. Garland and others have estimated that 15 minutes a day of sun exposure would prevent 10 cancer deaths for every one skin cancer death it would cause.

In December, a study involving 7 million whites in the U.S. military found that those with the highest levels of vitamin D in their blood were 62 percent less likely to develop multiple sclerosis years later than those with low levels of the vitamin.

Even seasonal flu now is being linked to the lack of sun exposure that occurs each year at northern latitudes. A September review article in the Epidemiology of Infection noted how seasonal flu peaks dramatically between November and February while, at about the same time, vitamin D levels in the blood drop off substantially, a decline attributed to the lack of sun exposure that occurs during winter months. Vitamin D is synthesized in skin when it is exposed to ultraviolet radiation. The paper said a lack of sun exposure during the winter also may contribute to susceptibility to other respiratory viral infections, including many of the more than 200 viruses that cause the common cold.